“When copper and copper alloy surfaces contact acidic foods, copper may be leached into the food,” the division notes.

High concentrations of copper are known to be poisonous and can cause food-borne illness. So the bulletin triggered nationwide hysteria, with newspapers headlines screaming: “YOUR MOSCOW MULE MUG COULD BE POISONING YOU”.

So, does it mean you need to kiss your favourite cocktail goodbye for the sake of your health?

Probably not.

There’s no real reason to worry about solid copper mugs killing you slowly.

It is true that the Moscow Mule’s pH is well below 6.0, due to its mix of vodka, ginger beer and lime, but most commercially available copper mugs are lined inside with tin or stainless steel, making them safe for drinking any acidic beverage.

Copper cup manufacturers know this. Most bar and restaurants know this. Iowa’s Alcoholic Beverages Division knows this and even stated it in the bulletin:

“However, copper mugs lined on the interior with another metal, such as nickel or stainless steel, are allowed to be used and are widely available.”

David Werning, a spokesperson for the Iowa Department of Inspections and Appeals, sought to play down the Moscow Mule-frenzy in a statement to NBC Connecticut:

“It’s not that if you drink a Moscow Mule from a copper cup, you’re going to die,” he said.

The bulletin was issued after an inspection of a restaurant in Ankeny, Iowa, found that copper mugs were being used behind the bar.

Since the mugs were tarnished and pitted, the Division issued the state-wide advisory to create universal guidelines for public restaurants and bars in line with the Food & Drug Administration — which has generally been adopted in every other state.

Most chefs and mixologists already know this, and avoid copper-plated pots because they can alter the flavour of food.